The invention relates to a method of essentially sterile packaging fluid or powdery products, in particular foodstuffs or beverages, in a packaging material in the form of a pouch of foil material having a filler opening closable by a closure cap, and to a pouch of foil material for use in such method.
It is known to store liquid or paste-like cleaning materials in flexible refill pouches so as to keep an accumulation of packaging materials to as low a level as possible for environmental reasons. Refill pouches of this type may be in the form of pouches that can be cut open or may include a weld pourer element having a closure cap so that it is possible to repeatedly open and close the refill pouch. In this field of application, flexible pouches naturally do not give rise to sterilisation problems. By contrast however, for health reasons and in order to achieve a sufficiently long shelf-life, problems predominate in the packaging of foodstuffs and beverages for human consumption. Until now, such products were mainly stored in rigid containers made of glass or sheet metal because these are easy to sterilise. Such containers can of course be easily recycled. However, a not inconsiderable level of environmental pollution is associated with the collecting of empty containers and the return thereof to a recycling plant. Moreover, the heavy and voluminous containers cause difficulties in regard to the transportation and storage thereof. Consequently, there is a need for a packaging for foodstuffs and beverages in the form of flexible pouches similar to the known refill pouches used for cleaning materials, which can easily be disposed wihout the shelf-life of the foodstuffs or beverages is substantially reduced by use of these flexible pouches. Although in the EP-A-0 661 208, which discloses a method of manufacturing a flexible pouch including a closure cap and the filling thereof in a filling plant, mention is made that the known procedure be suitable for packaging products such as milk, cooking oils and the like, it is not explained how a sufficient shelf-life can be ensured in packages of this type, even if the manufacture of the pouch would be effected in extremely, sterile surroundings and the products were subjected to a sterilisation treatment prior to filling. In addition, there is a tendency in the foodstuff industry to subject foodstuffs to a germ-killing or sterile treatment without invoking long periods of high temperature for various reasons (retention of valuable substances, such as vitamins, no loss of aroma etc.), so that complete freedom from germs cannot be ensured for the product, and consequently correspondingly greater demands on freedom from germs must be applied to the packaging itself.
The object of the invention is to develop a method which complies with the aforesaid demands of the foodstuff industry, in that it now shall be possible foodstuffs and beverages to be stored in flexible pouches in an economic and environmentally friendly manner without the shelf-life being substantially reducing thereby.
The method according to the present invention is characterised by the following steps:
providing a pouch in which the closure cap can be placed in a first and second sealing position relative to the filler opening, whereby the closure cap is removable without a destruction thereof from the filler opening in at least the first position,
treating in a germ-killing manner the interior of the empty substantially flat pouch having the closure cap in its first position,
conveying the pouch having the closure cap in its first position and its interior treated in said germ-killing manner to a filling plant wherein the following further treatment operations are performed:
treating a germ-killing manner the exterior of the pouch having the closure cap in its first position at least in a portion including the closure cap and the filler opening,
removing the closure cap from the pouch,
filling the product into the pouch through the filler opening, and
re-placing the closure cap onto the filled pouch and closing the filler opening by moving the closure cap into its second position.
The method according to the invention will be explained in more detail hereinafter.
The starting material is a peripherally sealed e.g. a hot sealed, flexible pouch having a pourer insert element permanently attached thereto by welding, this being referred to hereinafter for short, as a weld pourer element, and a closure cap which can be mounted on said weld pourer element by being knocked thereon so as to seal and close a filler opening which is defined by the weld pourer element and provides access to the interior of the pouch. The construction of a preferred pouch suitable for use in the method of the invention will be described in more detail hereinafter. The pouch may, for example, have a volume of between 0.3 and 5.0 1 although this should not be considered as being a limitation on the invention.
The flat empty pouch having a closure cap located in a first of two closure positions, both of which seal the inlet opening, is initially, i.e. prior to further treatment in a filling plant, subjected to a germ-killing treatment, preferably using germ-killing xcex3-rays, in a radiation station which could be of basically known construction and consequently does not need to be described in more detail. The germ-killing treatment may be effected during the manufacture of the pouch or, if so desired, immediately prior to the entry of the pouch into the filling plant. The purpose of the treatment is to produce a germ-free state, or as germ-free a state as possible, in the interior of the pouch. Since the closure cap occupying its first closure position hermetically seals the interior of the pouch, this germ-free state will be retained for further treatment of the pouch even if a long period of time, e.g. of some days or even several months, should elapse between the germ-killing operation and further treatments.
A number of pouches pre-treated in the manner previously described can be brought together to form a transportation pack for subsequent insertion into a storage magazine of a filling plant, whereby an annular collar on the weld pourer element provides an abutment support by means of which the pouch can be inserted by hand or in some other manner into a rail-like intake of the magazine of the filling plant with the weld pourer element facing upwardly. The pouches are transferred successively from the magazine of the filling plant to a transportation device, whereby the annular collar serves for supporting the pouches during transportation in order to move the pouches one after the other through a plurality stations in which further treatment is effected.
The transportation device preferably comprises a rotary table having a plurality of treatment stations disposed around the periphery thereof. In a first treatment station, the pouch with its closure cap still occupying the first position is subjected to an external germ-killing treatment by being sprayed with a liquid disinfectant by means of a jet on at least that portion of the pouch comprising the closure cap and the weld pourer element. The disinfectant may be any one of the substances known in the food industry so that one may dispense with a more detailed explanation in this regard.
Following the germ-killing treatment of the exterior of the pouch, subsequently there is a drying step in a drying station in which hot air or hot steam is applied to the pouch.
The so pre-treated pouch is transported thereafter to a station in which grippers grasp the closure cap and remove it from the weld pourer element. The removed closure cap is fed into a bypass transportation path and temporarily stored there so that it can be re-placed on the pouch at a later time.
Following thereon, the pouch with the closure cap removed therefrom reaches a filling station in which the product e.g. a foodstuff or a beverage, is introduced into the interior of the pouch through the open filler opening of the weld pourer element.
Thereafter, and prior to the closure cap being re-placed, an inert gas e.g. nitrogen or steam is fed into the interior of the filled pouch in a further station in order to expell any remaining air in the pouch and thereby counteract undesirable oxidation of, or other forms of alteration to, the filling.
Following this treatment, the closure cap is picked up from the bypass transportation path by means of a gripper device in a closing station and re-placed on the filled pouch, and mounted such that the closure cap adopts its second sealing position wherein it either cannot be removed from the weld pourer element or can only be removed therefrom by application of considerable force, possibly destroying the weld pourer element.
If so desired, a drying treatment by hot air or steam may be performed in a drying station following the last treatment step, prior to the filled and hermetically sealed pouch leaving the filling plant for further use.
It is preferred, that the treatment in at least those stations in which the closure cap is removed from the pouch, the pouch is filled with a product and the closure cap is re-placed on the filled pouch, in essentially germ-free surroundings is effected by keeping these handling stations screened from the outer surroundings in so far as possible. The transportation of the pouch through the individual treatment stations and the treatments effected therein may be effected automatically under the control of a process controlling device. Basically, in regard to the construction of such a filling plant and said treatment stations, the skilled person may revert to known means, so that more detailed explanation thereof can be dispensed with.